1. Field of Invention
The present invention relates to a method for optimizing a wireless distribution system. More particularly, the present invention relates to a method for optimizing a wireless distribution system, wherein a new wireless distribution system link is dynamically added such that the wireless distribution system network can give the optimized performance.
2. Description of Related Art
Distribution System (DS) is defined in IEEE802.11 specification as a system for linking two different Basic Service Sets (BSS). Referring to FIG. 1, for BSS3 and BSS4 in the right half, the manner of linking their Access Points (AP) BSS3AP and BSS4AP with network cables is referred to as a DS. And for BSS1 and BSS2 on the left half, their APs BSS1AP and BSS2AP are linked in a wireless manner, which is referred to as a Wireless Distribution System (WDS).
The wireless AP having the WDS function is different from a common AP in that it has multiple roles, i.e. besides for serving the mobile clients, it can also be WDS linked with other APs directly, to expand the existing service range of the wireless network. As shown in FIG. 1, BSS3AP (the AP of BSS BSS3) builds a WDS link (WDS Link2 as shown) with BSS1AP (the AP of BSS BSS1), and also builds another WDS link (WDS Link1 as shown) with BSS2AP (the AP of BSS BSS2), so the AP BSS4AP can communicate with the AP BSS2AP through the forwarding of the WDS. And the notebook connected to the AP BSS2AP (bss1NB as shown) can also be linked to the wired network on the right through the WDS.
Since the network cards at the same wireless AP have to use the same channel, the two BSSs linked through the AP have to use the same channel, and that is the reason why BSS1, BSS2 and BSS3 all use the same channel in FIG. 1.
The operation of the WDS is to communicate with each other through a frame including four addresses. Referring to FIG. 2A, the frame includes several fields such as a Frame Control field, a Duration/ID field, an Address 1 field, an Address 2 field, an Address 3 field, a Sequence Control field, an Address 4 field, a Frame Body field and a Frame Check Sequence (FCS) field. In the frame, the numbers of Octets in each field are respectively: 2 Octets in the Frame Control field, 2 Octets in the Duration/ID field, 6 Octets in the Address 1 field, 6 Octets in the Address 2 field, 6 Octets in the Address 3 field, 2 Octets in the Sequence Control field, 6 Octets in the Address 4 field, 0˜2312 Octets in the Frame Body field, and 4 Octets in the FCS field.
The content in the four address fields are as shown in FIG. 2 respectively. The WDS frame in the drawing includes SA representing a media access control (MAC) address of a source terminal, DA representing a MAC address of a destination terminal, TA representing a MAC address of an AP for forwarding frames, and RA representing a MAC address of a receiving terminal AP.
Taking FIG. 1 as an example, if a client terminal bss2NB connected with the access point BSS2AP within BSS2 is going to send data to another client terminal bss1NB connected with the access point BSS1AP within BSS1, the frame content will includes in sequence: the MAC address of the BSS1AP, the MAC address of the BSS2AP, the MAC address of the destination client bss1NB and the MAC address of the source client bss2NB.
The BSS2AP inquires through a WDS table of itself, forwards the frame to BSS1AP, and then sends it to the destination client bss1NB.
The following is the flow of configuring a WDS in the prior art:
(1) Before configuration, inquire and write down the wireless MAC addresses of the access point BSS1 AP and the access point BSS2 AP.
(2) Start the WDS function of BSS1 AP and BSS2 AP.
(3) Add each of the MAC addresses to the WDS Table of the other party.
(4) Configure two APs for using the same channel.
(5) Restart.
The existing wireless network AP have to configure its MAC Table and adjust the Channel settings manually when configuring the WDS Link, meanwhile, it can not perform optimize when adding or reducing the nodes.